Kinetic Study on the Heavy Metal Ions Removal from Aqueous Solutions Using Multi-Walled Carbon Nanotubes

Abstract

Kinetic study on the removal of zinc(II), copper(II), lead(II) and cadmium(II) from the aqueous solutions using multi-walled carbon nanotubes (MWNTs) was carried out to examine the temperature effect on the adsorption of zinc(II), copper(II), lead(II) and cadmium(II) as well as to explore the potentiality of using carbon nanotubes as a promising adsorbent for environmental remediation. Multi-walled carbon nanotubes were characterized by BET (Brunauer-Emmett-Teller), FE-SEM (Field emission scanning electron microscopy), and DPASV (differential pulse anodic stripping voltammetry). Adsorption experiments were carried out and comparisons with the previous work were made. Experimental results showed that the multi-walled carbon nanotubes can successfully remove zinc(II), copper(II), lead(II) and cadmium(II) from aqueous solutions. Increasing solution temperature can significantly improve the removal efficiency because of the endothermic nature of adsorption process. The kinetics of zinc(II), copper(II), lead(II) and cadmium(II) adsorption on multi-walled carbon nanotubes were analyzed, and the calculation results showed that the heavy metal ions adsorption is a pseudo-second-order process, and its capacity increases with increasing solution temperature. The binding of the metal ions by the multi-walled carbon nanotubes was evaluated from the adsorption capacities and found in the following order: copper(II) > lead(II) > zinc(II) > cadmium(II). Finally, multi-walled carbon nanotubes demonstrated that they are a promising adsorbent for the removal of heavy metal ions from aqueous solutions.